Extrusion press container



March 14, 1961 R. M. L. ELKAN EXTRUSION PRESS CONTAINER 2 Sheets-Sheet 1Filed 001;. 9, 19.57

'Elkan,

R I o m 6 E fi 5 T 2 V T w lw WrA A Y MB D BM March 14, 1961 R. M. 1..ELKAN 74,7

EXTRUSION PRESS CONTAINER Filed Oct. 9, 1957 2 Sheets-Sheet 2 UnitedStates Patent EXTRUSION PRESS CONTAINER Robert Max Ludwig Elkan,Bournemouth West, England, assignor to The Loewy Engineering CompanyLimited, Bournemouth, England, a corporation of Great Britain Filed Oct.9, 1957, Ser. No. 689,194

Claims priority, application Great Britain Oct. 9, 1956 2 Claims. (Cl.207-) It is the general practice to use cylindrical billets as thestarting product from which metal billets are extruded on extrusionpresses. Consequently, the container of such a press, which receives thebillets to be extruded, has a billet chamber of circular cross-section.The casings of these containers have to be of substantial thickness inorder to withstand the large stresses which occur during an extrusionoperation, and these casings were, therefore, usually very big andcostly to manufacture. The Walls of the billet receiving chamber of acontainer are subjected to intensive wear because of their frictionalcontact under heavy pressure with the extruded metal. In'order to avoidthis wear taking place on the casing, which, as stated before, is anexpensive item, it is customary to insert into the casing a liner in theform of a substantially cylindrical sleeve made in one piece. In somecases, the liner is not fitted directly into the casing of thecontainer, but into an intermediate sleeve, called the liner holder. Theliner and casing, and, if provided, the liner holder, are assembledtogether with a forced fit.

It has been proposed to use, instead of cylindrical billets, billets ofrectangular cross-section, especially for the extrusion of articleshaving a cross-section whose overall width exceeds considerably itsoverall height. Such cross-sections can be more closely matched byrectangular billets than by circular billets, and this permits areduction in the extrusion pressure, and, thereby, in the tonnage of thepress which may be considerable. Presses for the extrusion ofrectangular billets must have a container with a rectangular billetchamber.

It has been found that the pattern of the distribution of stresses whichoccur in such a container during extrusion of rectangular billets is ofa special nature. This pattern is essentially difierent from that set upduring the extrusion of a circular billet inasmuch as it has pronouncedstress concentrations in those parts of the container which are adjacentthe corners of'the billet chamber, or adjacent the radial planes passingthrough those corners. If the part of the container comprising the wallsof a rectangular billet chamber were made in one single piece, this partwould, under the severe stress concentrations, soon develop cracks at ornear the corners or fracture altogether.

In order to avoid these stress concentrations and, at the same time, tofacilitate the machining of the container components, the proposal hasbeen made to position a plurality of inserts in a cylindrical cavity ofthe container of an extrusion press. These inserts have inner faceswhich are so shaped and spaced-apart from each other that the innerfaces of an assembly of inserts form together the walls of a rectangularbillet chamber of the desired size. Each insert of an assembly has thenat least one inner face forming part of one of the walls of the billetchamber, at least one arcuate outer wall which contacts the cylindricalcavity in the container, which may be either formed direct in thecasing, or in the liner, and at least two faces joining the inner to theouter face and in contact with mating faces of the adjacent inserts.

In view of the severe stresses to which the inserts are subjected duringextrusionoperations, they must be machined to very close tolerances tominimize clearances between adjacent inserts and between the inserts andthe surrounding container component. This makes the inserts expensive toproduce, especially as some of their faces may have to be of somewhatirregular shape. As the inserts are in direct contact with the billetmetal, and are therefore subjected to friction under extrusion pressure,in the same way as the liner of the conventional type of container,heavy wear occurs at the inner faces of the inserts, which shortens thelife of the inserts.

The present invention relates to certain improvements in a metalextrusion press container specially designed for receiving rectangularbillets and in which the billet chamber is formed by an assembly ofinserts positioned in a circular cavity inside the container.

One of the objects of the invention is to provide improvements whichmake the use of the inserts a more economical proposition than it hasbeen heretofore, by minimizing the wear at the inserts, and byfacilitating the replacement of worn parts.

The objects of the invention will become apparent from the followingspecification, in which embodiments of the invention are described byway of example with reference to the accompanying drawings.

In the drawings:

Fig. 1 is an end view of a container of an extrusion press into whichthe invention is incorporated,

Fig. 2 is a partial longitudinal section on an enlarged scale, alongline 22 of Fig. 1,

Fig. 3 is a transverse section along the line 3-3 of Fig. 2,

Fig. 4 is a section corresponding to that of Fig. 2 of anotherembodiment of the invention,

Fig. 5 is a transverse section along line 55 of Fig. 4.

As to be seen in Fig. l, a container for a metal extrusion presscomprises a casing 10 having a circular cavity 11 and a sleeve-shapedand substantially cylindrical liner 12 inserted into the cavity 11 witha forced fit. Alternatively, the liner 12 may not be directly insertedinto the casing 10, but into a likewise substantially cylindrical linerholder arranged intermediate the liner and the casing. The casing 10 hasa rectangular outline. The liner 12 has a cylindrical cavity 13.Positioned into that lastmentioned cavity is an assembly of inserts 14,15, 16 and 17, each of which has an inner face 14a, 15a, 16a and 17arespectively, and an outer face 14b, 15b, 16b and 17]) respectively, andtwo side faces 14c, 15c, 16c and 17c respectively, which join the innerand the outer faces. The inner faces 14a to 17a are plane-shaped andform together a rectangular opening oriented along a major axis XX and aminor axis YY. The outer faces 14b to 1717 are arcuate and in contactwith the cylindrical cavity 13. The side faces 14: to 17c of each insertare in close contact with mating side faces on the adjacent inserts.

According to the present invention, separate wearplates 18, 19, 20 and21 are arranged on the inner faces 14a to 17a of the inserts 14 to 17respectively. These Wear-plates extend over the inner faces of theinserts so as to cover the latter entirely. Any contact of the insertswith the hot billet metal is, therefore, avoided, and the inserts arenotsubjected to Wear which otherwise would result from this contact. Anywear is limited to the wear-plates.

The wear-plates 18 to 20 have here the form of rectangles with paralleland plane surfaces. They are therefore easy to machine and can be formedfrom ordinary strip.

, It is to be understood that the thickness of the wear-plates is suchthat they form together, when in position on their respective inserts,-a rectangular chamber 22 of the size required for the accommodation ofthe rectangular billets to be extruded from the press. The height of theinserts can therefore be correspondingly reduced.

Means are provided for attaching the wear-plates to their associatedinserts in such -a manner that the wearplates can withstand the forcesto which they are subjected, especially during extrusion, withoutbecoming dislodged from the inserts.

In one form of the invention, shown in Figs. 1 and 2, the wear-plateshave at their ends outwardly projecting lips 23 and 23 which enter intocorrespondingly shaped recesses in the respective inserts so as not toprotrude over the end-faces of the inserts. If desired, the lips may beextended in the radial direction beyond the inserts so that they engageand enter into further outlying parts of the container assembly. Thelips have the purpose of preventing axial displacement of thewear-plates relative to the inserts and they may be fastened to theinserts, as shown in Figs. 1 and 2, by such means as screws 24.

Instead of or in addition to the lips, the wear-plates may be attachedto the inserts 14', 15', 16' and 17 by means of dowel pins or screws,the latter being shown at 25 in the embodiment according to Figs. 4 and5. In the case of dowel pins or screws 25 being provided, the end screws24 may be dispensed with, but the wear-plates 18, 1,, 20' and 21 maystill be formed with lips 23 and 23', whereby the pins or screws 25 arerelieved from side thrusts and shear stresses. The lips provided at thedie end of the container assembly are firmly held against the die or thedie holder by the pressure with which the container is forced intosealing contact with the die in a manner generally known with extrusionpresses of conentional types. The die has been indicated at 26 and thedie holder at 27 in Figs. 2 and 4.

As a further alternative means for attaching the wearplates to theinserts, shrinking may be used.

In all cases, the wear-plates can be readily removed from theirassociated inserts without damaging the latter, so that the insertsremain intact and can be used with another set of wear-plates.

As a rule, a single wear-plate is provided in respect of each insert,the wear-plates extending well over the entire area of the inner face ofthis insert. Alternatively, especially in the case of inserts havinglarge inner faces, a plurality of smaller wear-plates may be provided inrespect of each insert, whereby manufacturing of the in serts isfacilitated, it being then, for instance, possible to make the insertsfrom narrower strip than would otherwise have been possible.

Conversely, a common wear-plate may be provided for a number of inserts.It may, for instance, be of advantage, especially in the case ofcontainers of great axial length, to sub-divide the inserts into anumber of sections arranged in axial alignment, one behind the other.These sections can be made much smaller and lighter than one insertwhich extends along the entire length of the container, and theirmanufacturing will he therefore correspondingly simpler and less costly.The sections forming together one insert may then have a commonwearplate attached to their insides, which covers the joints betweenadjacent sections.

The sub-division of the inserts, which is rendered possible through theprovision of the wear-plates, allows it further to utilize the same setof sectionalized inserts for billet containers of different length, oneor more sections of suitable length being then added to make up for theincrease in length of the container. In this way, the number of insertsto be kept in stock for catering for billets of different length can beconsiderably reduced.

The present invention makes it further possible to exchange a wear-plateof a certain thickness for another one of ditferent thickness, withoutchanging the insert. In this way, the dimensions of the billet chamberformed by the wear-plates may be altered within certain limits, withouthaving to use a fresh set of inserts. This again reduces the number ofinserts which have to be kept in stock.

An extrusion press having a container embodying the present inventioncan therefore be more readily adapted for the extrusion of billets ofdifierent sizes, than was formerly possible. In view of the highmanufacturing costs of the inserts, it has been hitherto deemeduneconomical to provide special and separate sets of inserts fordifferent sizes of billets, especially when the variation in billet sizewas only comparatively small, i.e., in the order of an inch or less.This has sometimes been an obstacle to the use of rectangular billets onextrusion presses, and has not permitted to take full advantage of theadaptability of the cross-section of rectangular billets to that of theextruded articles.

A set of inserts, as shown in the drawings, consists of four pieces,'one for each side of the rectangular billet chamber, so that normallyfour wear-plates will be provided. It is possible to exchange theneither all four wear-plates together, or only a pair of plates whichface each other. In exceptional cases, it may also be feasible to take awear-plate, or pair of wear-plates, out altogether. In this way, thesize of the billet chamber defined by the wear-plates can be readilyvaried.

After the surface of a wear-plate has become worn, the wear-plate can bedetached from its insert, and machined down to the thickness which isrequired for forming a billet chamber of the next larger size. One andthe same Wear-plate can therefore be used in succession for differentbillet chambers and its useful life thereby correspondingly increased.

The side-walls of the wear-plates, with which they are in contact witheach other, may be chamfered so that they extend substantially in thedirection of diagonals of rectangles.

What is claimed is:

1. A billet container forran extrusion press comprising: an outer casingwith a cylindrical cavity therethrough, a cylindrical liner assembledwithin said cavity, two pairs of inserts positioned in said liner, saidinserts each having an arcuate outer surface fitting against the insidebore of said liner, two obliquely disposed fiat, side surfaces, and aflat inner surface, each insert of one pair of said inserts being ateach of its obliquely disposed sides in abutting contact with theobliquely disposed side of one of the inserts of the other pairs ofinserts, and the flat inner surfaces of all of said inserts cooperatingwith each other to define a first rectangular cavity separated from saidliner at all four sides by said inserts, said inserts meeting at thecorners of said rectangular cavity, whereby corner stresses in saidrectangular cavity are relieved, and two pairs of fiat rectangularplates secured in said first rectangular cavity to line and cover thesame thus forming an innermost second rectangular cavity for thereception of a billet, two of said plates being opposed to one anotherand each being in abutting contact with three of said inserts, the othertwo of said plates being opposed to one another and each being inabutting contact with only one of said inserts, each of said platesbeing in abutting contact with two of the other plates, whereby saidsecond rectangular cavity will, under extrusion pressure, be sealed fromthe oblique junctions of said inserts.

2. A billet container according to claim 1, in which said flatrectangular plates are provided with outwardly protruding lips which arein engagement with the ends of said inserts for preventing axialdisplacement of said plates relative to said inserts.

References Cited in the file of this patent UNITED STATES PATENTS 6Jones Sept. 26, 1916 Clark May 19, 1942 Sequin Nov. 27, 1945 Schlecht eta1. May 17, 1955 Swanson Ian. 6, 1959 FOREIGN PATENTS Great Britain Get.2, 1957 France May 3, 1907

